LIGEMDIO (LIGht EMitting DIOde) is a through-hole and surface-mount LED tester soldering kit. in its default setup, it can test through-hole LEDs through the top holes, and any size two-terminal SMD LED. The solder-blob jumpers can enable an input of a PWM signal and testing of common-anode RGB LEDs.
The circuit is based around a simple two-BJT constant current driver, shown on the back of the PCB. It can be powered from USB or external power input.
More information on the kit, including assembly and programming tutorials are here. (Or get the infographic PDF.)
This design, as always, is also open source hardware; it's available on our GitHub repository.